The function and structure of the hamster submandibular (parasympathetic) ganglion will be studied with electrophysiological and morphological techniques. The synaptic potentials evoked in response to a single preganglionic stimulation are either monophasic deplorizing potential or biphasic potential which is composed of an inital deplorizing phase followed by a small hyperpolarizing phase (Suzuki & Kusano, 1978). However, when a brief repetitive preganglionic stimulation e.g., at 10 Hz for 3 sec) is applied, unusually complicated, multiphased (4 to 5 phases) synaptic potentials which have a total duration of more than 10 min, comprising tens of milliseconds to several minutes are evoked (unpublished). This proposal aims to study the properties of these long lasting synaptic potentials in vitro. In order to characterize the postsynaptic receptors responsible for each synaptic potential phase, various putative transmitters (cholinergic, adrenergic and peptidergic, etc.) and inhibitors are applied to the neurons through perfusion or iontophoretically. Ionic mechanisms of the various phases of the PSP will be analyzed with either current or voltage clamp technique. Several morphological and histochemical techniques will be incorporated during various phases of electrophysiological experiments in order to correlate the structure of the ganglion with synaptic functions. The physiological function of various phases of the PSP will be studied in the in vivo, combining with reflex discharges which can be induced by increasing the ambient temperature or by applying taste stimuli to the animal.